The present invention relates to the art of vehicle anti-theft devices and systems and, more particularly, to systems producing an audio and/or visual alarm in response to unauthorized entry into, or attempted unauthorized entry into a vehicle.
The present invention finds particular utility in connection with detecting the unauthorized entry into the driver and passenger compartment of a vehicle and, accordingly, will be described in detail herein in connection with such use. At the same time, however, it will be appreciated that the invention has other utility such as detecting the unauthorized opening of a vehicle compartment enclosure such as a door for the driver and passenger compartment, the hood closing a vehicle motor compartment and/or a vehicle trunk lid.
Over the past several years, there has been an increasing demand by vehicle owners for security devices to deter or prevent vehicle theft and unauthorized entry into the interior of a vehicle or into the engine compartment or trunk. A wide variety of anti-theft devices and systems have been developed in an effort to minimize the foregoing and other security problems. Such devices include, for example, steering wheel locks, alarm systems and devices which disable certain components of the vehicle when a theft is attempted, and electronic security systems which actuate an alarm in response to the detection of vibration or other motion of the vehicle when the security system is activated. Steering wheel locks are of course a good deterrent against theft of a vehicle in that they preclude steering thereof. At the same time, they do not preclude a thief from breaking into the vehicle driver and passenger compartment or opening the hood and/or trunk for the purpose of stealing items such as radio equipment, the vehicle battery, a spare tire and any other valuable objects which may have been left in the vehicle. The electronic systems heretofore provided are intended, primarily, to deter unauthorized entry into any compartment of the vehicle and, in this respect, function in response to vibration of the vehicle to actuate horns, sirens and/or blinking lights to frighten a would be thief away. A persistent problem with such vibration responsive security systems is the difficulty to adjust the sensitivity thereof so that they are neither over or under sensitive. In this respect, if they are too sensitive, the alarm can be actuated by wind or other minor movement of the vehicle. On the other hand, if they are not sensitive enough, it is possible to carefully gain entry to the vehicle without setting the alarm off. This sensitivity problem negatively affects the efficiency of such a security system for its intended purpose and negatively affects customer acceptance of such systems as a viable deterrent to unauthorized entry and/or theft of a vehicle or articles therein. In particular in this respect, the actuation of such alarm systems in response to movement of a vehicle other than that created by a would be thief has become prevalent to the extent that the audio and/or visual alarms are often ignored by persons who might otherwise intervene and/or take notice of a thief so as to be able to identify the latter to authorities.